1. Field of the Invention
The present general inventive concept relates to an apparatus and method of motion-compensation adaptive deinterlacing, and more particularly, to an apparatus and method of motion-compensation adaptive deinterlacing in which motion adaptive deinterlacing and motion-compensation deinterlacing are combined to convert interlaced video into progressive scan video.
2. Description of the Related Art
The recent development of digital TV technology and large-screen display devices, such as plasma digital panel (PDP) TVs and projection TVs using digital lighting processing (DLP), liquid crystal display (LCD), and liquid crystal on silicon (LCoS), allows users to enjoy high-definition (HD) video. With the wide spread of such digital video devices, an environment where analog video devices, such as traditional TVs, and digital video devices coexist has become commonplace. Thus, processing with respect to conventional analog NTSC (National Television Systems Committee) screens or standard definition (SD) screens is also required. Since conventional analog TV video generally uses interlaced scanning, a resolution or scanning rate should be improved to adapt to an HD screen. To this end, conversion from the interlaced scanning to progressive scanning is effective.
The interlaced scanning and the progressive scanning are classified according to a method of constructing a frame. In the interlaced scanning, each of two fields is composed of odd or even scan lines and a frame is constructed by interlacing the even scan lines from one field between the odd scan lines from the other field. In other words, the odd scan lines are scanned for one field (a top field), the even scan lines are scanned for the other field (a bottom field), and a frame is constructed using the two fields. On the other hand, in the progressive scanning, a frame is constructed by progressively scanning the lines of a video signal. The progressive scanning has less flicker than the interlaced scanning.
Various algorithms have been developed for conversion from the interlaced scanning to the progressive scanning. For example, there are an algorithm that repetitively uses line information of a current field, an algorithm that inserts line information of a previous field, an algorithm that extracts an edge from video information of a current field and performs interpolation along an edge direction of the edge, a motion-adaptive deinterlacing algorithm, and a motion compensation algorithm. Here, deinterlacing refers to a process of converting interlaced video into progressive scan video.
The algorithm that repetitively uses the line information of the current field is often used in the progressive scanning on a computer screen, but may output step pattern images in a diagonal still picture. The algorithm that inserts the line information of the previous field is also mainly used in the progressive scanning on the computer screen, but may output a double image.
FIGS. 1A through 1C are views illustrating conventional algorithms for converting interlaced video into progressive scan video. FIG. 1A is a view illustrating a conventional deinterlacing algorithm using interpolation along an edge direction. FIG. 1B is a view illustrating a conventional motion adaptive deinterlacing algorithm. FIG. 1C is a view illustrating a conventional motion-compensation deinterlacing algorithm.
As illustrated in FIG. 1A, the conventional deinterlacing algorithm using interpolation along the edge direction does not create a pixel through simple linear interpolation, but instead detects the edge direction and performs interpolation along the detected edge direction with respect to a pixel p(x,y). The conventional deinterlacing algorithm of FIG. 1A removes artifacts from final output video using interpolation along the edge direction and can be implemented with simple hardware. However, in the case of a still image, since this algorithm provides an image quality that is inferior to the conventional motion adaptive deinterlacing algorithm or the conventional motion-compensation deinterlacing algorithm, it is usually combined with the conventional motion adaptive deinterlacing algorithm or the conventional motion-compensation deinterlacing algorithm in HD digital TV applications.
Referring to FIG. 1B, the conventional motion adaptive deinterlacing algorithm determines whether a pixel c[t(n−2)] to be interpolated is moving using a plurality of input fields (i.e. first, second, and third fields) and performs interpolation using pixel information a1[t(n−2)], a[t(n−2)], ar[t(n−2)], b1[t(n−2)], b[t(n−2)], and br[t(n−2)] of a previous field if the pixel c[t(n−2)] to be interpolated is static, or using video information a1[t(n)], a[t(n)], ar[t(n)], b1[t(n)], b[t(n)], and br[t(n)] of lines above and below a line including the pixel c[t(n−2)] to be interpolated in a current field if the pixel c[t(n−2)] to be interpolated is moving. The conventional motion adaptive deinterlacing algorithm can be easily configured with hardware and offers a good price/performance ratio. However, when there is a motion in an image, the output image quality of the conventional motion adaptive deinterlacing algorithm is inferior to that of the conventional motion-compensation deinterlacting algorithm. Moreover, since a pixel should be synthesized only using information within a frame, if there is a little motion, it is impossible to take full advantage of given information.
Referring to FIG. 1C, the conventional motion-compensation deinterlacing algorithm extracts motion information D(x,t) according to a searching area SA from a previous field or a next field of a current field including a pixel to be interpolated and performs interpolation in a direction of motion. Since the performance of the motion-compensation deinterlacing algorithm depends on accurate motion detection, the optimal image quality can be assured with accurate motion estimation. However, the actual hardware configuration for extracting motion information is difficult to implement. Moreover, since inaccurate motion estimation directly leads to quality degradation, it is not easy to use the conventional motion-compensation deinterlacing algorithm in actual applications.